What materials will I need for a hydronic baseboard heating system?

I am installing a hydronic baseboard heating system and I would like to use a tankless water heater as opposed to a boiler for the energy source. Will this work? Also, I am assuming copper is the material of choice for the piping, but what would I use as the reflective backing material behind the pipe?

Tankless water heaters are mediocre at supplying both domestic hot water and hydronic heat.

Quietside makes one that is decent, but save your money and get the Triangle Tube Prestige Excellence (a boiler that heats water) and you will be much happier. Runtal and many others make flat-panel radiators that outperform any other hydronic heat delivery system, and they are beautiful.

Yes, Virginia, copper is the best, but that cheesy plastic stuff works well, too. Caleffi has a website that is chock-full of info about this and anything else you could imagine hydronically. I also recommend their stuff over any others.